What was found
DURING TRAINING FLT, DURING 1 MANEUVER, NOTICED VARIOUS ANNUNCIATORS FLICKER ON & OFF. NOTICED SMOKE COMING OUT OF GLARE SHIELD. FOLLOWED CHECKLIST & IMMEDIATELY TURNED BATTERY & MASTER GENS TO EMER, SMOKE STOPPED. OPENED MANUAL PRESSURE KNOB & SMOKE EXITED COCKPIT. DECLARED AN EMERGENCY & VECTORED BACK TO AIRPORT. TURNED BATTERY BACK ON TO GET MLG DOWN & FULL FLAPS DOWN & ACCOMPLISHED A NORMAL APPROACH. MX FOUND "EMER WARN LT" & "COPLT WARN" CIRCUIT BREAKERS TRIPPED. FOUND DIODES CR655 & CR656 ON TERMINAL BOARD TB107 MELTED. DIODES REPLACED. NO CAUSE FOR MELTED DIODES DETERMINED, AS A PREVENTATIVE MEASURE 3 ASSOCIATED CIRCUIT BOARDS REPLACED.